ENGLISH NATURE The management of sembnatural lowland grassland for selected rare and scarce vascular plants A review No. 216 - English Nature Research Reports working today for nature tornorrow English Nature Research Reports Number 216 The management of semi-natural lowland grassland for selected rare and scarce vascular plants: a review English Nature Contract no. Low /5.1 (G) T. C. C. Rich ISSN 0967-876X Q Copyright English Nature 1997 Contents 1. Introduction .............................................................. i 2 . Methods and information sources ............................. 1 2.1 Methods .............................................................. i 2.2 Information sources ............................................... 2 3 . Species accounts ..................................................... 3 3.1 Aceras anthropophorum - Man orchid ............................ 3 3.2 Epipactis atrorub~ns- Dark-red helleborine ..................... 5 3.3 Gentianella anglica - Early gentian ............................... 9 3.4 Heminiurn monorchis - Musk orchid ........................... 13 3.5 Himantoglossum hircinum - Lizard orchid ...................... 14 3.6 fieris amara - Candytuft ......................................... 17 3.8 Ophrys fucifzora - Late spider-orchid........................... 20 3.9 Qphrys sphegodes - Early spider-orchid ......................... 23 3. 10 Orchis ustulata - Burnt orchid ................................... 25 3.11 Polemonium caertcleum - Jacob's-ladder ......................... 27 3.12 Pulsatilla vulgaris - Pasque flower .............................. 29 3.13 Teucriunz botrys - Cut-leaved germander ....................... 32 3.14 Veronica spicata subsp . spicata Breckland spiked speedwell ......................................................... 34 3.15 Veronica spicata subsp . hybrida - Western spiked speedwell ......................................................... 36 3.16 Diagrammatic summary of life cycles ........................... 38 4. Glossary ............................................................... 41 5 . Acknowledgements ............................................... 41 6. Bibliography ......................................................... 42 1. Introduction Lowland semi-natural grassland provides a habitat for a number of nationally rare and scarce vascular plants. The first edition of the Lowland pwssland n7nnapmnf handbook (Crofts & Jefferson 1994) provided guidance on iiiany aspects of grassland management but gave little specific advice on individual plant species. The aim of this report is to draw together ecological and management information on fourteen rdre or scarce vascular plant species for the sccond edition. The species selected partly reflect those for which advice on management is most often requested (eg orchids) or where requirements may differ from the 'normal' habitat management regimes. The species are Acerns aizthropophorum (Man orchid), Epipncf is ntrorubms (Dark-red helleborine), Genfiinnella anglicn (Early gentian), Herriziriium nioriorrhis (Musk orchid), Hima~ztoglossurnhirriizunz (Lizard orchid), Iberis anzara (Candytuft), Linum pererrire subsp. niiglirunz (Perennial flax), Ophiys firciflorcr (Late spider-orchid), Ophqs sphcgodes (Early spider-orchid), Orchis usfulata (Burnt orchid), IJolernoizium caeruleunz Uacob's ladder), Pirlsnfilla nirlgaris (Pasque flower), Teucriunz bof ys (Cut-leaved germander), and the two subspecies of Veroizica spicnfrn (Spiked speed well), subsp. spicata and subsp. hybridn. The objectives of this report were to: carry out a literature search for information relating to the autecology and habitat management requirements of the species. s collate relevant information from nature reserve managers and research workers. draw up habitat management prescriptions for each species. 2. Methods and information sources 2.1 Methods The accounts have been drawn up in a standard format for each species reviewing the status, life cycle, distribution, ecology and practical management details. There is a variable amount of information available about each species and some are much better known (e.g. I-'ulsafilla) than others (eg Hewrziiiiunz). A diagrammatic summary of thc life cyclcs of individual species is given in Figure 1 (Section 3.16); the precise times of leaf, flower and fruit production will vary between sites and seasons. When drawing up management plans information should be collated both from a literature search and from contacts with relevant expcrts and land managers to review all the available information before making any decisions (a plant in the land is worth two in the book). Primary sources of information and direct experience are always preferred to second-hand knowledge. Many land managers have practical experience of whether individual species increase or decrease under particular regimes, and it is essential to draw on their knowledge. Sharing information and experience can have benefits for all. Understanding the life cycle is critical. Plants may be annuals, biennials or short- or long- lived perennials, and may flower once only (monocarpic) or many times (polycarpic). Some short-lived plants may also be a little plastic in these respects, and may behave differently in cultivation to the wild (eg Teucrimm botrys). 'hetimes at which each species produces leaves, 1 flowers and fruits should be taken into account when deciding the timing of management work or grazing. Some species reproduce by seed alone, some by both seed and vegetative growth, and a few can spread vegetatively without producing seed. In the former two cases, allowing the populations to produce both flowers and ripe seed is clearly essential. The presence of a seed bank is especially important for restoration management. For many species research and carefill observation is required to determine which stages in the life cycle are the critical fxtors which actually limit reproduction; it is notable that many rare orchids produce very few ripe seed pods due to limited pollination. An understanding of natural population cycles, which may vary according to the life cycle and climate in addition to management, is also valuable and may require observation over a period of five years or more. Ideally the management should aim to maximise reproductive output and the amount of suitable habitat. The vegeta tion structure and composition, especially the height and amount of bare ground, are often critical for grassland species and can be obtained from known healthy populations. A range of environmental factors can affect plants from drought to soil types and lierbivory, and knowledge of these can help explain unexpected changes in populations, such as the effects of drought on population cycles in Gentianella and Hernziniunz. It inay however only be possible to control some factors suclz as stock grazing regimes; if sites are to be grazed, then knowledge of the palatability of the plants to different types of stock is critical. There is no substitute for practical experience of management, especially when this is coupled with detailed population studies. Although there is often much published about the ecology and life cycles of individual species, suitable management regimes are rarely documented in the literature. Management is also often a compromise between different requirements of the different plants, animals or habitats on the sites and it is important to be clear which are the priorities. Management regimes are often unique to each reserve due to the sheer practicalities of management, especially where land or stock are not owned, but the general principles can often be applied elsewhere. As many species can survive in a range of regimes, even if sub- optimal, details of a range of inanagement regimes can enable compromises to be reached if needed. Optimum as opposed to adequate management on particular sites is often an iterative process which can only be carried out by trial and error. The main forms of management arc grazing, mowing, con trolled burning, disturbance and non-intervention (for full details see Crofts & Jefferson 1994). For Fazing regimes both the stocking (stock type, numbers of animals per hectare, timing) and swards heightslcondiiion are useful to allow suitable habitat conditions to be obtained from either the stock or the grassland. For mowing, the timing and height of cutting and whether cuttings should be removed should be considered. For controlled burning the time of year and frequency are important as these affect the temperature of the fire which may affect the plants. Disturbance in the form of ploughing, rotovation, chain harrowing, clearing saws, hand digging, etc. needs also to be carried out at specific times of year prior to germination. A few sites such as sea cliff top psslands require no intervention. The recommendations for management regimes are based on current best advice, and may need to be revised in light of further information which would be welcomed. 2 2.2 Information sources The literature search for relevant information was carried out by a computer search on BIDS, a search through local and national floras, BSBI Abstracts, the bibliographical index of the British flora (Simpson lYhO), biological floras in the joiirizal of Ecolocgy, English Nature's library catalogue, etc. References traced are listed in the bibliography (Section 5); a small number mainly relating to European work which not been seen are listed separately at the end of the bibliography. Contacts were made with